Grab mechanisms



March 4, 1958 K. H. DENT GRAB MECHANISMS 2 Sheets-Sheet 1 Filed Oct. 20, 1955 I March 4, 1958 K. H. DENT GRAB MECHANISMS 2 Sheets-Sheet 2 Filed 001:. 20, 1955 [GRAB MECHANISMS Kenneth Henry Dent, Warrington, England, assignor, by i mesnecassignments, .to the UnitedStates of America as represented by; the" United-States vAtomic Energy vCommission Application ctober'2'0, 1955, :Serial No." 541,792

14' Claims. (Cl.v 294-86) .This;invention relatesitograbmechanisms and-it ispar- .ticularlyzconcerned -.with grapplingarticles having-:radial :arms and located. inside: a': narrow vertical channel- "with very limited accessability.

. vThe;-grab.: mechanism accordinggtouthe inventionacomprises a body-part supportingarrotor, an electricalrsystem for producing a fiux to move ;the rotor. relative to thexbody part, and I 'tWO concentrically mounted: sleeves, the .first depending. from the body part and the second adapted- 1o be rotated relative to thefirst by coupling with the rotor, vsaid sleevestogether defining slots forming :a:latching. meansfor grapplingnan article with radial armsqunder control .ofithemovementofsaid rotor.

An embodiment of the invention ,willnowbedescribcd with reference to the drawings wherein:

Fig. 1 is a sectionalzelevation.

Fig. 2 is a view in the direction of arrow II of Fig. 1.

Fig. 3 is a sectional view on the line III-III of Fig. 1.

Fig. 4 is a wiring diagram.

In Fig. 1 an electromagnetically operated grab shown in the energised position has a smooth contoured mildsteel body and a mild-steel rotor 11. A solenoid winding 12 is arranged to produce a flux as indicated by the dotted lines 13. This flux traverses the body 10 and rotor 11 and also traverses teeth 14 and teeth 15 on the body and rotor (see also Fig. 3). A sleeve 16 is screwed to a ring 17 bolted to the body 10. A non-magnetic stainless steel sleeve 19, coaxial with the sleeve 16, is bolted on to the rotor 11 by bolts 18. The sleeve 19 is provided with three bayonet slots 20 having lead-in slots 21 (refer also to Fig. 3). The sleeve 16 has three plain slots 22 arranged to correspond with the lead-in slots 21. Both sleeves have fairings 23, 24 leading to the slots 21, 22. A probe 25 is carried through the rotor. This probe is loaded by a spring 26 and couples with a push rod 27 which has a loose sliding fit in the rotor 11. The push rod 27 has a faced end 28 which moves over contact members 29, 30 of switches 31, 32 so that switch 31 is operated before switch 32 when the push rod 27 rises. The rotor moves against a spring 33 fitted to a screw 34 in a ring 47 and to pegs in a plate 35 held by dowels 36 in the rotor. The limit of movement of rotor is determined by the pegs contacting adjustable stops 46 supported from the ring 47.

The rotor is carried in angular contact bearings 37, 38 in bushes 54 of non-magnetic material. The teeth 14 and 15 are fixed to the body 10 and rotor 11 respectively by keys 39, 40. The switches 31, 32 are mounted on a plate 41. The unviewed side of the plate 41 has a terminal block 49 into which is coupled a cable 42 through an aperture 50 in the plate 41. The cable 42 has steel reinforcement. A connection 43 passes via a duct 48 from the winding 12. The cable 42 passes through a cable clamp 44. A removable top cover 45 is provided having an overhanging web 51 and fairings 52.

In Fig. 2 the provision of three sets of slots 21, 22 are shown. The fairings 24 on the sleeve 16 extend around the circumference of the sleeve whilst the fairings 23 on i United .States ..P...atent I t 2,825,599 Patented =Maiap4".;19'5s 'the sleeve l9 extend onlypartially-around the circumference. Bolts "18*and probe 25 are-also shown.

In FigJ3 the'rotor 1-1 is shown in the positionjit takes up when thewinding 12 'is' energised. The flux-path is showniby the dotted line 13 and conventional 'tail and point signs 53. Otheritems shown on this figure, which are also shown in Fig. 1,-aretlie-key 39, the teeth 14 and 15 and 'the duct48. Itis arranged that the rotor teeth 15 are olfset' by"'6 from the teeth'14 on the body -part 10, in the; energised position. lnthexdeenergised position-the =oifset;is 20.

- lnzthewiringdiagram 'ofFig. 4 components numbered 12, 31,..32,:142, Aland 49 havetheir mechanical equivalents in similarly numbered components in Fig; l. Gutside these components there is a rectifier 54 coupled with the solenoid winding 12 to prevent tfalse: energisation of athe coilz onicurrentireversals. The axle ofaawinchfis shownzbytheidotted line:.55. .Itis'sby the :winch that :the .grahwShQwnain-:-Eig..11sis raised and-lowered on the cable 42. .Ihiscableds connectedtozslip rings56 havingzbrushesi,57 ;and-:c9nnections15861;as shown. The connec- On 1- i madetto avlamp: L1 and :thence to.,a.bat teryi62. The conneqtipmfi lzisz madeJo a relay; A having two conmm Al and-A2- .Ihcrrelay: connects viaan-o erators .foot switchFS ito-thegbattery .62. C0nnection 59 is also made to.tthe atte ya 2 zhubby way; ,Of a ,cam; switchrCs,

.a: ,manual override; switch 5 MO. and. the, switch -FS. The switch CS is operated from a rotargcam. drive ;through .gearing fromthe ,winchaxle. ,Both .the switch CSand .theswitchMQhavethree m ior-pcs t on .an rmalpo 'tion N, 'a' grab release position RLSE and a grab pick up position PU; a lamp L2 is provided to indicate when the coil 12 is energised.

For the description of the operation of the circuit of Fig. 4 and the grab it is assumed that the grab is in a normal mid-way position and is to descend to pick up a vertical tube provided at the top with a three-armed spider, lift the tube by the spider and release it into a container at a higher level. The electrical condition of the circuit is as-shown in Fig. 4 at the start of the operation. The winch is started to lower the grab and switch FS is depressed so that the battery potential (50 volts) appears on the moving arm of the switch CS. At a point determined by the rotary cam, and before the spider arms enter into slots 21, 22 (Fig. 1) the switch CS reaches the PU position, the coil 12 is energised, the lamp L2 hghts and slots 21, 22 are made to coincide. As the grab is lowered the arms of the spider pass into the slots 21, 22, which have been opened to receive them, and the boss of the spider contacts the probe 25 and the switch 31 operates. 'lhis lights the lamp 1.1 which indicates to the operator that the object has entered the grab. The grab is then further lowered until the arms or the object are fully inserted in the slots 21, 22.

The switch 32 then closes, the relay A is energised, contact A1 closes so that the relay is held operated regardless of contact 32 and contact A2 moves so that the coil 12 is de-energized. Under the tension of springs 33 (Fig. l) the grab closes to latch the arms of the spider into the bayonet slot. The lift can now take place. Upon lifting, the spider arms drop into the bottom of the bayonet slots and switch 32 opens. The relay A remains energised via its holding contact A1 until the operator opens switch FS.

For the release operation, the spider is grounded. The arms rise in the bayonet slots so that switch 32 reoperates and the switch FS is also operated. Relay A is energised and so is the coil 12 through the switch CS in the RLSE position. As the grab is lifted away from the spider the switch 32 opens followed by the switch 31 and the lamp L1 is extinguished. When the operator releases 3 switch FS relay A releases and the apparatus is ready for another lifting operation.

For the reverse operation of lowering a spider another grab is provided, of similar construction to that described above but with the cam -switching modified to allow a pick-up at the top of the travel and a release at the bottom. In lieu of two grabs it would be possibleto arrange a reversing switch mechanism between the switch CS and the contacts A2 or, alternatively, arrangements could be made for advancing and retarding the cam operating the switch CS with a reversing driveto the cam.

The operation of the apparatus has been described on the basis of energising coil 12,to bring the slots 21, 22 in alignment and de-energisingthetcoil to-latch the arms of the spider in the bayonet slot. The reverse sequence would be possible but probably not so safe'a's failure of power to the coil 12 may result in droppingvthe object being lifted. j

1. A grab mechanism comprising a body part supporting a rotor; an electrical system for producing a flux to move the rotortrelative to the body part and two concentrically mounted sleeves, the first depending from the body part and the second adapted to be rotated relative to the first by a coupling with the rotor, said sleeves together defining slots that may in one relative position be aligned to permit entry therein of radial arms of a body having radial arms, and in another relative position of the slots, the slots are non-aligned to lock the radial arms in certain of the said slots, thereby forming alatching means for 'grappling an article with radial arms under control of the movement of said rotor.

2. A grab mechanism according to claim 1 wherein one of said sleeves is shaped to have a set of bayonet slots 9,825,599 7 t t i and the other is shaped to have plain slots corresponding with the lead-in part of said bayonet slots so that a body with radial arms can be grappled by first the simultaneous entry of the arms into the slots in both sleeves and then by the relative rotation of the sleeves to drive the arms into the holding part of the bayonet slots.

3. A grab mechanism comprising a body part supporting a rotor; an electrical winding for producing a flux to rotate the rotor relative to the body part; two concentrically mounted sleeves, the first attached to the body part and the second adapted to be rotated relative to the first sleeve by the rotor, one sleeve defining bayonet slots and the other defining plain slots corresponding with said bayonet slotstin a selected relative position of the sleeves so that a body with radial arms can be associated with the grab by the simultaneous entry of the arms into the slots; a probe slidably mounted in a passage through the axis of the rotor and sensitive to the degree of insertion of radial arms into the slots; a switch mounted on a plate supported by the body part' and arranged to be operated by said probe when said radial arms are fully inserted to change the state of energisation of said electrical winding so that the arms become 'latched in the bayonet slots by relative rotation of the sleeves, and means for counterrotating the sleeves to release the arms. 7

No references cited. 

